Tigecycline is a tetracycline derivative (a glycylcycline) which is a chemically (4S,4aS,5aR,12aS)-9-[2-(tert-butylamino)acetamido]-4,7bis(dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,10,12,12a-tetrahydroxy-1,11-dioxo-2-naphthacenecarboxamide. Molecular formula of Tigecycline is C29H39N5O8 and the molecular weight is 585.65 and has following chemical structure:

USRE40183 discloses 7-substituted-9-substituted amino-6-demethyl-6-deoxytetracyclines which cover Tigecycline. Tigecycline is marketed as lyophilized powder for reconstitution for intravenous infusion under trade name TYGACIL® by Wyeth; which contains Tigecycline as active ingredient and lactose monohydrate as inactive ingredient. Tigecycline is approved for complicated skin and skin structure infections, complicated intra-abdominal infections and community-acquired bacterial pneumonia.
From literature it is known that Tigecycline undergoes degradation by two different pathways. One of them is oxidative degradation and another one is epimerization. Oxidative degradation can be controlled by lowering pH of the composition. At lower pH, epimerization emerges as the most predominant degradation pathway. To overcome the said problem several approaches are reported as follows:
Tigecycline is currently marked as TYGACIL® by Wyeth; which contains lactose monohydrate as inactive ingredient. The pH of the composition after reconstitution is acidic. The composition uses lactose monohydrate as stabilizer to control the degradation of Tigecycline by epimerization pathways.
U.S. Pat. No. 7,879,828 discloses a composition comprising tigecycline, lactose, and an acid selected from hydrochloric acid and gentisic acid, and the pH of the composition in a solution is between about 3.0 and about 7.0. Focus of U.S. Pat. No. 7,879,828 is to use lactose and lower pH to get stable composition of Tigecycline.
U.S. Pat. No. 7,705,168 discloses a manufacturing process for the production of tigecycline as a reconstitutable powder having less than 0.9% total degradants comprising the steps of reducing and maintaining the oxygen level in water for injection to less than or equal to 0.5 ppm. Focus of U.S. Pat. No. 7,705,168 is to control oxidation pathway by controlling oxygen level.
US2009275660 discloses stable parenteral formulations of tigecycline and process of preparation thereof, wherein the formulation comprises of an edetate, a pH modifying agent or an antioxidant, such that the formulation remains stable for at least 45 hours. Focus of US2009275660 is to provide stable composition by using edetate.
US2010035845 discloses a frozen pharmaceutical formulation suitable for administration to a subject parenterally, comprising a therapeutically effective amount of tigecycline and an agent selected from the group consisting of lactose, dextrose, glucose, mannose, sucrose, ribose, xylose and a combination thereof.
Focus of US2010035845 is to use lactose, dextrose, glucose, mannose, sucrose, ribose, xylose to get stable composition of Tigecycline.
Considering the prior efforts as disclosed in the background, a need exists which would addresses the issues relating to degradation of Tigecycline in the pharmaceutical composition and provides a stable pharmaceutical composition of Tigecycline.